Semiconductor lasers are the fundamental building block in compact photonic and optoelectronic devices. Formed from Group III-V semiconductors, the semiconductor lasers emit laser light in response to electrical stimulation as electrons relax back to lower energy states and emit photons. Some semiconductor lasers use quantum wells, which confine carriers in a manner that forces the carriers to occupy an essentially planar two-dimensional region.
Quantum dots are currently used in optoelectronic devices to realize potential improvements in speed and extension of accessible wavelength ranges. The generation of terahertz frequencies is currently of interest in the Group III-V semiconductor field because of many potential applications in areas including national security and environmental sensing. The most successful device to date for generating terahertz frequencies is the quantum cascade laser which utilizes very precisely controlled, nanoscale structures in one-dimension. These structures are designed to facilitate intraband carrier recombination with transition energies in the terahertz regime. The quantum cascade lasers offer limited engineering control over the intraband band gaps.